The present invention relates to an apparatus for superfinishing true edges of cutting tools such as veneer lathes and veneer slicers, which have roughly been ground with a knife grinder.
Manual grinding with a flat grindstone is a traditional way for superfinishing the cutting edges of such tools. The manual grinding requires, however, skilled or experienced workers, and moreover, is both time- and labor-consuming.
Now machine superfinishing is conventionally carried out instead of the manual grinding, which employs spring elasticity or fluid pressure applied from a fluid cylinder to press a grinding wheel against the cutting edge. In this machine grinding, however, the dead weight of the grinding wheel is added to or subtracted from the applied pressure, that is, varies the pressure. The changeable pressure imparts vibrations to the grinding wheel as the wheel travels in the longitudinal direction of the cutting edge and may do damage to the cutting edge.
An example of the machine finishing is disclosed in JAPANESE PATENT PUBLICATION GAZETTE No. Sho-63-36903 under the title of `Method and apparatus for superfinishing cutting edges` by the Inventors. The apparatus disclosed therein temporarily releases fluid pressure, which is applied to a grinding wheel to press the cutting edge, when the grinding wheel is detected to reach an longitudinal end of the cutting edge, thus allowing the grinding wheel to make a desirable number of reciprocating motions. The fluid pressure temporarily released is again applied to the grinding wheel when the grinding wheel starts moving back in the longitudinal direction of the cutting edge. At that time, the resultant vector of a force for transferring the grinding wheel parallel to the longitudinal direction of the cutting edge and a downward force for pressing the grinding wheel onto the cutting edge is applied to the grinding wheel. Accordingly, the grinding wheel is obliquely transported and pressed on the end of the cutting edge. The bias motion of the grinding wheel may fail to grind the end of the cutting edge to a desired degree of superfine finish.
As described above, no prior art sufficiently or desirably superfinishes the cutting edge which has been roughly ground.